#include <stdio.h>
int main()
{
    int a = 0, b = 0, n = 0;
    double j = 0, sum = 0;
    scanf_s("%d", &n);
    for (a = 1, b = 1; a <= n; a++)
    {
        j = (double)b * a;
        b = j;
        double c = 1.0 / j;
        sum += c;
    }
    printf("%f", sum);
    return 0;
}